Abrasive articles, such as polishing or conditioning disks, are generally formed by affixing abrasive particles to a carrier or substrate with a matrix material. Such abrasive articles are used to smooth or polish the surface of a workpiece, such as a urethane pad, which may, in turn, be used to polish components, such as silicon wafers. Conditioning disks are used in a wide variety of environments including highly corrosive environments which degrade the structural integrity of the article. Thus, if the abrasive particles are not adequately secured to the substrate, the particles will have a tendency to become dislodged from the matrix material. Once dislodged, an abrasive particle can easily scratch and damage the polished surface of the workpiece. In addition, once one particle is dislodged, support for adjacent particles is decreased, and additional particles are more likely to become dislodged. Accordingly, a conditioning disk which maintains its strength, wear resistance, and structural integrity in a corrosive environment is highly desirable.
Various techniques have been used to affix abrasive particles to a substrate. Each technique includes surrounding the abrasive particles with a matrix material which forms a bond between the particles and substrate, thereby serving to hold the particles in place. One such known technique is electroplating which includes depositing a metal, typically nickel, to a thickness in the range of 40-75% of the height of the particle, thereby forming a bond with the abrasive particles which is a purely mechanical attachment. The Bruxvoort et al. U.S. Pat. No. 5,251,802, for example, discloses an abrasive article including a plurality of abrasive composites bonded to a backing. Each of the abrasive composites includes a plurality of abrasive grains, such as diamond or cubic boron nitride, and a preferably metallic binder of tin, bronze, nickel, silver, iron, and alloys or combinations thereof for securing the abrasive grains to the backing. The binder is applied to the backing by an electroplating process and the abrasive grains are applied simultaneously during the electroplating process. Electroplating is limited in that not all abrasive particles form adequate bonds with electro-deposited metal. In addition, not all metals are capable of electrodeposition, therefore limiting the range of metallic compositions which can be used in the electroplating process.
Another known technique for affixing abrasive particles to a substrate is by sintering the matrix material. Sintering involves applying heat and/or pressure to a fusible matrix material containing abrasive particles, thereby serving to affix the abrasive particles to the substrate. The Tselesin U.S. Pat. No. 5,380,390, for example, discloses an abrasive article and method in which the abrasive particles are affixed to a substrate by a sinterable or fusible matrix material. The Lowder et al. U.S. Pat. No. 5,511,718 discloses a process of brazing diamond to create monolayer tools with a nickel-chromium-boron alloy. While sintering generally serves to affix the abrasive particles to the substrate, the abrasive particles have a tendency to become dislodged from the matrix material during operation, particularly in a corrosive environment. Thus, there exists the need for a corrosion resistant abrasive article in which the abrasive particles remain affixed to the substrate over extended periods of operation under adverse operating conditions.